U.S. patent number 7,008,894 [Application Number 10/394,012] was granted by the patent office on 2006-03-07 for high permittivity dielectric ceramic composition and electronic device.
This patent grant is currently assigned to TDK Corporation. Invention is credited to Norio Sasaki, Yoshiharu Watanabe.
United States Patent |
7,008,894 |
Sasaki , et al. |
March 7, 2006 |
High permittivity dielectric ceramic composition and electronic
device
Abstract
A high permittivity dielectric ceramic composition wherein a
main component includes BaTiO.sub.3: 74.24 to 79.97 mol %,
BaZrO.sub.3: 5.69 to 12.04 mol %, CaTiO.sub.3: 7.84 to 12.13 mol %,
MgTiO.sub.3: 3.11 to 4.72 mol % and Bi.sub.2TiO.sub.5: 0.10 to 0.60
mol %. With respect to 100 wt % of the main component, 0.1 or less
(excepting 0) of NiO, 0.1 wt % or less (excepting 0) of CeO.sub.2,
and 0.2 wt % or less (excepting 0) of MnO are included. In
accordance with need, 0.2 wt % or less (excepting 0) of SiO.sub.2
is further included with respect to 100 wt % of the main component.
A high relative permittivity, such as 9000 or more, a high AC
breakdown voltage, and a small electrostatic capacity change rage
with respect to temperature can be obtained.
Inventors: |
Sasaki; Norio (Tokyo,
JP), Watanabe; Yoshiharu (Tokyo, JP) |
Assignee: |
TDK Corporation (Tokyo,
JP)
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Family
ID: |
28035834 |
Appl.
No.: |
10/394,012 |
Filed: |
March 24, 2003 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20030191011 A1 |
Oct 9, 2003 |
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Foreign Application Priority Data
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Mar 26, 2002 [JP] |
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2002-084678 |
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Current U.S.
Class: |
501/138;
501/139 |
Current CPC
Class: |
H01G
4/1245 (20130101); C04B 35/4682 (20130101); C04B
35/49 (20130101); C04B 35/6262 (20130101); C04B
2235/3418 (20130101); C04B 2235/3267 (20130101); C04B
2235/3208 (20130101); C04B 2235/3229 (20130101); C04B
2235/3206 (20130101); C04B 2235/3279 (20130101); C04B
2235/3248 (20130101); C04B 2235/3298 (20130101); C04B
2235/3215 (20130101); C04B 2235/3244 (20130101); C04B
2235/3262 (20130101); C04B 2235/3236 (20130101); C04B
2235/3234 (20130101); C04B 2235/3232 (20130101) |
Current International
Class: |
C04B
35/468 (20060101) |
Field of
Search: |
;501/137,138,139 |
References Cited
[Referenced By]
U.S. Patent Documents
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5604166 |
February 1997 |
Sasaki et al. |
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Foreign Patent Documents
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A-60-101803 |
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Jun 1985 |
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JP |
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A-02-123614 |
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May 1990 |
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JP |
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(A) 3-65558 |
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Mar 1991 |
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JP |
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(A) 7-267732 |
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Oct 1995 |
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JP |
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Primary Examiner: Group; Karl
Attorney, Agent or Firm: Oliff & Berridge, PLC
Claims
What is claimed is:
1. A high permittivity dielectric ceramic composition, comprising
0.1 wt % or less (excepting 0) of NiO, 0.1 wt % or less (excepting
0) of CeO.sub.2, and 0.2 wt % or less (excepting 0) of MnO with
respect to 100 wt % of a main component including BaTiO.sub.3:
74.24 to 79.97 mol % BaZrO.sub.3: 5.69 to 12.04 mol % CaTiO.sub.3:
7.84 to 12.13 mol % MgTiO.sub.3: 3.11 to 4.72 mol % and
Bi.sub.2TiO.sub.5: 0.10 to 0.60 mol % in total of 100 mol % of the
main component.
2. The high permittivity dielectric ceramic composition as set
forth in claim 1, wherein 0.2 wt % or less (excepting 0) of
SiO.sub.2 is further included with respect to 100 wt % of said main
component.
3. A high permittivity dielectric ceramic composition, comprising
0.1 wt % or less (excepting 0) of NiO, 0.1 wt % or less (excepting
0) of CeO.sub.2, and 0.2 wt % or less (excepting 0) of MnO with
respect to 100 wt % of a main component including BaTiO.sub.3:
74.38 to 79.79 mol % BaZrO.sub.3: 7.33 to 10.15 mol % CaTiO.sub.3:
8.34 to 12.13 mol % MgTiO.sub.3: 3.40 to 3.76 mol % and
Bi.sub.2TiO.sub.5: 0.10 to 0.60 mol % in total of 100 mol % of the
main component.
4. The high permittivity dielectric ceramic composition as set
forth in claim 3, wherein 0.2 wt % or less (excepting 0) of
SiO.sub.2 is further included with respect to 100 wt % of said main
component.
5. The high permittivity dielectric ceramic composition as set
forth in claim 3, wherein 0.04 to 0.10 wt % of NiO, 0.03 to 0.10 wt
% of CeO.sub.2, and 0.01 to 0.19 wt % (excepting 0) of MnO are
included with respect to 100 wt % of said main component.
6. The high permittivity dielectric ceramic composition as set
forth in claim 1, wherein a relative permittivity is 9000 or
more.
7. The high permittivity dielectric ceramic composition as set
forth in claim 3, wherein a relative permittivity is 9000 or
more.
8. An electronic device comprising a dielectric layer, wherein said
dielectric layer comprises 0.1 wt % or less (excepting 0) of NiO,
0.1 wt % or less (excepting 0) of CeO.sub.2, and 0.2 wt % or less
(excepting 0) of MnO with respect to 100 wt % of a main component
including BaTiO.sub.3: 74.24 to 79.97 mol % BaZrO.sub.3: 5.69 to
12.04 mol % CaTiO.sub.3: 7.84 to 12.13 mol % MgTiO.sub.3: 3.11 to
4.72 mol % and Bi.sub.2TiO.sub.5: 0.10 to 0.60 mol % in total of
100 mol % of the main component.
9. The electronic device as set forth in claim 8, wherein said
dielectric layer further comprises 0.2 wt % or less (excepting 0)
of SiO.sub.2 with respect to 100 wt % of said main component.
10. An electronic device comprising a dielectric layer, wherein
said dielectric layer comprises 0.1 wt % or less (excepting 0) of
NiO, 0.1 wt % or less (excepting 0) of CeO.sub.2, and 0.2 wt % or
less (excepting 0) of MnO with respect to 100 wt % of a main
component including BaTiO.sub.3: 74.38 to 79.79 mol % BaZrO.sub.3:
7.33 to 10.15 mol % CaTiO.sub.3: 8.34 to 12.13 mol % MgTiO.sub.3:
3.40 to 3.76 mol % and Bi.sub.2TiO.sub.5: 0.10 to 0.60 mol % in
total of 100 mol % of the main component.
11. The electronic device as set forth in claim 10, wherein said
dielectric layer further comprises 0.2 wt % or less (excepting 0)
of SiO.sub.2 with respect to 100 wt % of said main component.
12. The electronic device as set forth in claim 10, wherein said
dielectric layer comprises 0.04 to 0.10 wt % of NiO, 0.03 to 0.10
wt % of CeO.sub.2, and 0.01 to 0.19 wt % (excepting 0) of MnO with
respect to 100 wt % of said main component.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dielectric ceramic composition,
particularly relates to a high permittivity dielectric ceramic
composition wherein a relative permittivity is high as 9000 or
more, change in the relative permittivity with respect to
temperature is small, and an AC breakdown voltage is high.
2. Description of the Related Art
As a high permittivity ceramic composition broadly used as a
ceramic capacitor, multilayer capacitor, high frequency capacitor,
high-voltage capacitor, etc., conventionally, those having a
BaTiO.sub.3--CaTiO.sub.3--MgTiO.sub.3 base ceramic composition as a
main component have been practically used in general.
In BaTiO.sub.3--CaTiO.sub.3--MgTiO.sub.3 base dielectrics of the
related art, however, the electrostatic capacity change rate with
respect to temperature becomes large, when the relative
permittivity is made high as 6000 or more. Also, there is a
disadvantage that the AC breakdown voltage becomes low as 2.0 to
3.0 kV/mm.
The present inventors have proposed
BaTiO.sub.3--CaTiO.sub.3--MgTiO.sub.3 base dielectric ceramic
compositions as disclosed in the Japanese Unexamined Patent
Publications (kokai) No. 3-65558 and No. 7-267723, but the relative
permittivity did not reach 9000 in neither of the inventions.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a high
permittivity dielectric ceramic composition having a high relative
Permittivity as 9000 or more, high AC breakdown voltage and small
electrostatic capacity change rate with respect to temperature, and
a capacitor and other electronic devices using the same as a
dielectric layer.
To attain the above object, according to a first aspect of the
present invention, there is provided a high permittivity dielectric
ceramic composition, comprising 0.1 wt % or less (excepting 0) of
NiO, 0.1 wt % or less (excepting 0) of CeO.sub.2, and 0.2 wt % or
less (excepting 0) of MnO with respect to 100 wt % of a main
component including
BaTiO.sub.3: 74.24 to 79.97 mol %
BaZrO.sub.3: 5.69 to 12.04 mol %
CaTiO.sub.3: 7.84 to 12.13 mol %
MgTiO.sub.3: 3.11 to 4.72 mol % and
Bi.sub.2TiO.sub.5: 0.10 to 0.60 mol % in total of 100 mol % of the
main component.
According to the first aspect of the present invention, a
dielectric ceramic composition having excellent properties, such as
a high relative permittivity of 9000 or more, small electrostatic
capacity change rate with respect to temperature, high insulation
resistance and breakdown voltage, small dielectric loss and
preferable sintering property, can be obtained.
According to a second aspect of the present invention, there is
provided a high permittivity dielectric ceramic composition,
comprising 0.1 wt % or less (excepting 0) of NiO, 0.1 wt % or less
(excepting 0) of CeO.sub.2, and 0.2 wt % or less (excepting 0) of
MnO with respect to 100 wt % of a main component including
BaTiO.sub.3: 74.38 to 79.79 mol %
BaZrO.sub.3: 7.33 to 10.15 mol %
CaTiO.sub.3: 8.34 to 12.13 mol %
MgTiO.sub.3: 3.40 to 3.76 mol % and
Bi.sub.2TiO.sub.5: 0.10 to 0.60 mol % in total of 100 mol % of the
main component.
According to the second aspect of the present invention, a
dielectric ceramic composition having excellent properties, such as
a high relative permittivity of about 9200 or more, small
electrostatic capacity change rate with respect to temperature,
high insulation resistance and breakdown voltage, small dielectric
loss and preferable sintering property can be obtained.
In the second aspect of the present invention, preferably, 0.04 to
0.10 wt % of NiO, 0.03 to 0.10 wt % of CeO.sub.2, and 0.01 to 0.19
wt % (excepting 0) of MnO are included with respect to 100 wt % of
the main component. In this case, the relative permittivity becomes
particularly high and the insulation resistance and sintering
property also improve.
In the first and second aspects of the present invention,
preferably, 0.2 wt % or less (excepting 0) of SiO.sub.2 is further
included with respect to 100 wt % of said main component.
The insulation resistance and breakdown voltage are improved by
being contained SiO.sub.2. Note that it is preferable not to
contain SiO.sub.2 to improve the relative permittivity and
sintering property.
An electronic device according to the present invention comprises a
dielectric layer and the dielectric layer is comprised of the above
high permittivity dielectric ceramic composition.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A high permittivity dielectric ceramic composition according to an
embodiment of the present invention comprises 0.1 wt % or less
(excepting 0) of NiO, 0.1 wt % or less (excepting 0) of CeO.sub.2,
and 0.2 wt % or less (excepting 0) of MnO with respect to 100 wt %
of a main component including
BaTiO.sub.3: 74.24 to 79.97 mol %
BaZrO.sub.3: 5.69 to 12.04 mol %
CaTiO.sub.3: 7.84 to 12.13 mol %
MgTiO.sub.3: 3.11 to 4.72 mol % and
Bi.sub.2TiO.sub.5: 0.10 to 0.60 mol % in total of 100 mol % of the
main component.
Preferably, the above main component includes BaTiO.sub.3: 74.38 to
79.79 mol %
BaZrO.sub.3: 7.33 to 10.15 mol %
CaTiO.sub.3: 8.34 to 12.13 mol %
MgTiO.sub.3: 3.40 to 3.76 mol % and
Bi.sub.2TiO.sub.5: 0.10 to 0.60 mol %.
When a content of BaTiO.sub.3 in the main component is too small,
there are tendencies that the relative permittivity declines, the
electrostatic capacity change rate with respect to temperature
becomes large and the breakdown voltage also declines. Inversely,
when the content is too great, there are tendencies that the
dielectric lose deteriorates by becoming large, the breakdown
voltage becomes low and the electrostatic capacity change rate with
respect to temperature becomes large.
When a content of BaZrO.sub.3 in the main component is too small,
there are tendencies that the dielectric loss is deteriorated by
becoming large, the relative permittivity becomes low and the
electrostatic capacity change rate with respect to temperature
becomes large. While when the content becomes too great, there are
tendencies that although the dielectric lose becomes small, the
relative permittivity becomes low, the insulation resistance
becomes small, and the breakdown voltage becomes low.
When a content of CaTiO.sub.3 in the main component is too small,
there are tendencies that the relative permittivity becomes small,
the insulation resistance becomes small and the breakdown voltage
deteriorates. Inversely, when the content is too great, there are
tendencies that the relative permittivity becomes small and
insulation resistance becomes small.
When a content of MgTiO.sub.3 in the main component is too small,
there are tendencies that the insulation resistance becomes small,
the breakdown voltage declines, and the electrostatic capacity
change rate with respect to temperature becomes large. Inversely,
when the content is too great, there are tendencies that the
relative permittivity deteriorates and sintering property also
deteriorates.
When a content of Bi.sub.2TiO.sub.5 in the main component is too
small, there are tendencies that the dielectric loss is
deteriorated by becoming large, electrostatic capacity change rate
with respect to temperature becomes large, and the insulation
resistance declines. Inversely, when the content is too large,
there are tendencies that the relative permittivity declines,
breakdown voltage becomes low, and sintering property becomes
poor.
Furthermore, in the present invention, by making preferably 0.04 to
0.10 wt % of NiO, 0.03 to 0.10 wt % of CeO.sub.2 and 0.01 to 0.19
wt % (excepting 0) of MnO contained with respect to 100 wt % of the
main component, particularly the relative permittivity becomes high
and also the insulation resistance and the sintering property are
improved.
The dielectric ceramic composition may further include not more
than 0.2 wt % (including 0) of SiO.sub.2 with respect to 100 wt %
of the main component. When SiO.sub.2 is included, the insulation
resistance and breakdown voltage tend to improve, while when
SiO.sub.2 is not included, the relative permittivity and sintering
property tend to improve.
A production method for producing the dielectric ceramic
composition of the present invention is not particularly limited
and a general production method used in a production method of
ceramic capacitors and multilayer ceramic capacitors may be
used.
For example, as dielectric materials which are used to produce the
dielectric ceramic composition, materials composing a main
component and materials composing additive components
(subcomponents) are used in accordance with the composition of the
above dielectric ceramic composition. As the materials composing
the main component, oxides of Ti, Ba, Zr, Ca, Mg and Bi and/or
compounds which become oxides by being fired are used. As the
material composing the subcomponents, oxides of Ni, Ce, Mn and Si
and/or compounds which become oxides by being fired are used.
These dielectric materials are measured so that a composition after
fired becomes the above composition and mixed. The mixture is
calcined. After that, the mixture is granulated to be powder by a
well known method, then the powder is molded and fired so that a
ceramic element (dielectric layer) composed of a dielectric ceramic
composition can be obtained.
The ceramic capacitor can be obtained by forming electrodes on both
surfaces of the ceramic element.
Alternately, the above dielectric materials are mixed with an
organic vehicle to be used as a dielectric paste so that a green
chip is produced with a separately prepared internal electrode
paste by a normal printing method or a sheet method. After firing
the green chip, external electrodes are printed or transferred so
that a multilayer ceramic capacitor can be obtained.
EXAMPLE
Below, examples of the present invention will be explained. First,
a production procedure of a high permittivity dielectric ceramic
composition according to the examples of the present invention will
be explained.
As starting materials, barium carbonate (BaCO.sub.3), titanium
oxide (TiO.sub.2), zirconium oxide (ZrO.sub.2), calcium carbonate
(CaCO.sub.3), magnesium carbonate (MgCO.sub.3), bismuth oxide
(Bi.sub.2O.sub.3), nickel oxide (NiO), cesium oxide (CeO.sub.2),
manganese oxide (MnO) and silicon oxide (SiO.sub.2) were used.
These starting materials were measured so that compositions after
fired become compositions shown in Table 1 and Table 2, the
obtained blends of materials were wet mixed in a pot mill for 16
hours, then dehydrated, dried and calcined at 1140.degree. C. to
1200.degree. C. to bring chemical reaction.
The results were finely milled again in a pot mill, dehydrated and
dried, added polyvinyl alcohol (PVA) as an organic binder,
granulated and sized so that particle powders were obtained. The
particle powders were molded with a molding pressure of 300 MPa to
be disks having a diameter of 16.5 mm and a thickness of 1.1 mm.
The molded materials were fired at 1280 to 1360.degree. C. in the
air, and ceramic elements were obtained.
The thus obtained ceramic elements were formed with electrodes on
both end surfaces thereof by baking a silver (Ag) paste, leads were
soldered thereon to obtain ceramic capacitor samples. Electric
properties of the thus obtained capacitor samples were measured.
The results are shown in Table 1 and Table 2.
TABLE-US-00001 TABLE 1 Insulation Breakdown Electrostatic Relative
Dielectric Resistance Voltage Capacity Change Main Component (mol
%) Additives (wt %) Permittivity Loss IR (.OMEGA.) .times. AC Eb
(KV/ Rate .DELTA. C/C20 (%) Sintering Sample No. BaTiO3 BaZrO3
CaTiO3 MgTiO3 B12TiO5 NiO CeO2 MnO2 SiO2 .delta. s tan .delta. (%)
10.sup.11 mm) -25.degree. C. +85.degree. C. Property *1 *73.86
11.08 11.28 3.48 0.30 0.04 0.03 0.05 0.05 *8590 *1.9 *1.8 *3.2 -58*
-55 .largecircle. *2 74.66 10.14 11.68 3.52 *0.00 0.04 0.03 0.05
0.05 9400 *2.5 *1.1 4.5 -60* -41 .largecircle. 3 74.58 10.14 11.68
3.52 0.10 0.04 0.03 0.05 0.05 9310 1.6 2.1 5.1 -54 -54-
.largecircle. 4 74.38 10.15 11.68 3.51 0.30 0.04 0.03 0.05 0.05
9280 1.6 2.2 5.8 -54 -53- .largecircle. 5 74.24 10.13 11.63 3.40
0.60 0.04 0.03 0.05 0.05 9210 1.4 2.7 5.9 -52 -54- .largecircle. *6
74.24 10.13 11.63 3.40 0.60 *0.30 0.03 0.05 0.05 9420 1.2 2.5 *3.8
-49 -61* .largecircle. *7 74.24 10.13 11.63 3.40 0.60 0.04 *0.15
0.05 0.05 9320 1.3 2.3 4.1 -52 -58* .largecircle. 8 74.24 10.13
11.63 3.40 0.60 0.10 0.03 0.05 0.20 9350 1.0 2.0 4.2 -51 -53-
.largecircle. 9 74.24 10.13 11.63 3.40 0.60 0.04 0.10 0.05 0.05
9230 1.3 3.4 4.6 -54 -53- .largecircle. *10 74.24 10.13 11.63 3.40
0.60 0.04 0.03 *0.50 0.05 *7820 *2.1 *1.3 *3.8 - -47 -49 X 11 74.24
10.13 11.63 3.40 0.60 0.04 0.03 0.20 0.05 9190 1.3 2.9 4.4 -54 -5-
4 .largecircle. *12 74.24 10.13 11.63 3.40 0.60 0.04 0.03 0.05
*0.50 *7580 1.4 2.7 *3.9 -4- 7 -45 X *13 75.34 9.22 10.23 4.21
*1.00 0.04 0.03 0.05 0.05 *8670 0.7 3.1 *3.7 -39- -54 X *14 79.13
*4.22 *12.40 3.73 0.32 0.04 0.03 0.05 0.05 *8730 *3.6 1.9 *3.1 -57*
-47 .largecircle. 15 76.29 5.69 12.00 3.70 0.32 0.04 0.03 0.05 0.05
9020 1.7 1.9 5.5 -54 -50- .largecircle. *16 74.91 8.09 11.25 *5.25
0.50 0.04 0.03 0.05 0.05 *8120 1.7 2.5 5.1 -52 - -51 X 17 78.95
6.54 9.32 4.72 0.47 0.04 0.03 0.05 0.05 9140 1.6 2.3 5.2 -55 -50 -
.largecircle. 18 76.48 7.33 12.13 3.61 0.45 0.04 0.03 0.05 0.05
9380 1.1 3.8 5.3 -53 -54- .largecircle. 19 79.79 7.64 8.34 3.76
0.47 0.04 0.03 0.05 0.05 9830 1.2 2.1 4.9 -55 -55 - .largecircle.
*20 79.79 7.64 8.34 3.76 0.47 *0.30 0.03 0.05 0.05 9570 1.0 2.5
*3.7 -53 -59* .largecircle. *21 79.79 7.64 8.34 3.76 0.47 0.04
*0.15 0.05 0.05 9410 1.1 2.1 4.1 -52 -80* .largecircle. 22 79.79
7.64 8.34 3.76 0.47 0.10 0.03 0.05 0.20 9390 1.0 2.8 4.7 -53 -54 -
.largecircle. 23 79.79 7.64 8.34 3.76 0.45 0.04 0.10 0.05 0.05 9310
1.3 3.1 4.6 -52 -54 - .largecircle. *24 79.79 7.64 8.34 3.76 0.47
0.04 0.03 *0.50 0.05 *8650 1.1 *1.6 *3.8 -48- -51 X 25 79.79 7.64
8.34 3.76 0.47 0.04 0.03 0.20 0.05 9290 1.1 2.7 4.5 -54 -54 -
.largecircle. *26 79.79 7.64 8.34 3.76 0.47 0.04 0.03 0.05 *0.50
*8270 1.2 *1.8 4.1 -48 - -43 X 27 75.14 11.09 10.94 3.52 0.31 0.04
0.03 0.05 0.50 9120 1.0 3.9 5.4 -44 -5- 4 .largecircle. *28 77.26
11.82 *6.82 3.70 0.40 0.04 0.03 0.05 0.05 9140 1.2 3.2 *2.4 -54
-57* .largecircle. *29 77.11 10.42 10.26 *2.00 0.20 0.04 0.03 0.05
0.05 9070 1.3 *1.4 *2.8 -4- 9 -59* .largecircle. 30 78.33 7.82
11.87 3.57 0.31 0.04 0.03 0.05 0.05 9230 1.2 4.4 5.1 -52 -53-
.largecircle. 31 77.13 7.42 12.04 3.11 0.30 0.04 0.03 0.05 0.05
9400 1.5 3.1 4.1 -54 -54- .largecircle. *32 74.28 7.12 *15.26 3.04
0.30 0.04 0.03 0.05 0.05 *7430 1.4 *1.0 5.0 -49- -48 .largecircle.
33 79.27 9.15 7.84 3.22 0.51 0.04 0.03 0.05 0.05 9510 0.9 2.0 4.4
-47 -53 - .largecircle. *34 *81.07 7.55 7.87 3.18 0.33 0.04 0.03
0.05 0.05 9060 *2.9 3.4 *2.1 -59* -52 X *35 75.26 *12.82 *7.82 3.70
0.40 0.04 0.03 0.05 0.05 *7500 0.7 *0.9 *4.0 -- 42 -48 X
TABLE-US-00002 TABLE 2 Relative Main Component (mol %) Additives
(wt %) Permittivity Sample No. BaTiO3 BaZrO3 CaTiO3 MgTiO3 B12TiO5
NiO CeO2 MnO2 SiO2 .delta. 36 76.33 7.82 11.97 3.57 0.31 0.01 0.03
0.05 0.00 9130 37 76.33 7.82 11.97 3.57 0.31 0.04 0.03 0.05 0.00
9330 38 76.33 7.82 11.97 3.57 0.31 0.10 0.03 0.05 0.00 9370 *39
76.33 7.82 11.97 3.57 0.31 *0.30 0.03 0.05 0.00 9690 40 76.33 7.82
11.97 3.57 0.31 0.04 0.01 0.05 0.00 9030 41 76.33 7.82 11.97 3.57
0.31 0.04 0.03 0.05 0.00 9280 *42 76.33 7.82 11.97 3.57 0.31 0.04
*0.15 0.05 0.00 9400 43 76.33 7.82 11.97 3.57 0.31 0.04 0.03 0.05
0.00 9580 44 76.33 7.82 11.97 3.57 0.31 0.04 0.03 0.01 0.00 9460 45
76.33 7.82 11.97 3.57 0.31 0.04 0.03 0.05 0.00 9310 46 76.33 7.82
11.97 3.57 0.31 0.04 0.03 0.20 0.00 9180 *47 76.33 7.82 11.97 3.57
0.31 0.04 0.03 *0.50 0.00 *7200 48 76.33 7.82 11.97 3.57 0.31 0.04
0.03 0.05 0.05 9300 49 76.33 7.82 11.97 3.57 0.31 0.04 0.03 0.05
0.2 9110 *50 76.33 7.82 11.97 3.57 0.31 0.04 0.03 0.05 *0.5 *7900
Insulation Breakdown Electrostatic Dielectric Resistance Voltage
Capacity Change Loss IR (.OMEGA.) .times. AC Eb (KV/ Rate .DELTA.
C/C20 (%) Sintering Sample No. tan .delta. (%) 10.sup.11 mm)
-25.degree. C. +85.degree. C. Property 36 1.1 4.4 5.0 -53 -53
.circleincircle. 37 1.0 3.0 4.4 -52 -54 .circleincircle. 38 0.8 2.0
4.3 -51 -55 .circleincircle. *39 0.8 2.0 *2.9 -50 -60* X 40 1.2 6.5
5.5 -52 -52 .circleincircle. 41 1.1 6.5 5.5 -52 -53
.circleincircle. *42 1.0 4.3 4.9 -61 -61* .largecircle. 43 0.8 2.1
4.1 -50 -54 .circleincircle. 44 1.0 3.4 4.7 -53 -53
.circleincircle. 45 1.1 4.8 4.3 -54 -51 .circleincircle. 46 1.3 2.2
4.3 -54 -45 .circleincircle. *47 *2.5 *1.1 4.3 -49 -45 X 48 1.3 4
5.7 -53 -53 .circleincircle. 49 1.2 5.5 4.7 -51 -50
.circleincircle. *50 1.1 3.2 *3.2 -48 -45 X
Note that in measurements of the respective electric properties in
Table 1 and Table 2, the relative permittivity (es) and dielectric
loss (tan .delta.) were measured by using an LCR meter under
conditions of a frequency of 1 KHz, voltage of 1 kHz and a voltage
of 1 V and the insulation resistance (IR) was measured by applying
an AC voltage of 500V. Also, the breakdown voltage was measured as
an AC breakdown voltage (AcEb) per a unit thickness. Furthermore,
as to the electrostatic capacity change rate, an electrostatic
capacity of the capacitor samples was measured at a voltage of 1 V
when the reference temperature was set 20.degree. C. by using an
LCR meter and a change rate % of the electrostatic capacity was
obtained at temperatures of -25.degree. C. and +85.degree. C.
As to the sintering property, samples fired at a firing temperature
of 1320.degree. C. were examined and those having poor sintering
property are checked "X", good sintering property are checked
".smallcircle." a and particularly good wintering property are
checked ".circleincircle.". The standard of judging the sintering
property was defined as below. Namely, "X" was checked when the
sintered density was less than 5.9 g/cm.sub.3 or 6 or more out of
10 samples were insufficiently sintered, ".smallcircle." was
checked when the sintered density was not less than 5.5 g/cm.sup.3
or 0 or less out of 10 samples were insufficiently sintered, and
".circleincircle." was checked when the sintered density was not
less than 5.55 g/cm.sub.3 or 0 or less out of 10 samples were
insufficiently sintered.
In Table 1 and Table 2, samples with "*" mark added to their sample
numbers indicate that they are out of a preferable range of the
present invention. Note that in Table 1 and Table 2, the preferable
ranges of the properties were set to be the relative permittivity
of 9000 or more, the dielectric loss of 1.7 or less, the insulation
resistance of 1.9.times.10.sup.11 .OMEGA. or more, the breakdown
voltage of 4.1 or more, and the electrostatic capacity change rate
of within -55%.
Evaluation
As shown in the sample number 1 in Table 1, when a content of
BaTiO.sub.3 in the main component was less than 74.24 mol %, it was
confirmed that the relative permittivity as widely declines to be
less than 9000, the electrostatic capacity change rate with respect
to temperature becomes larger than -55% at -25.degree. C., and the
breakdown voltage deteriorates to be less than 4.1 kV. Furthermore,
in the sample number 1, it was confirmed that the dielectric loss
was more than 1.7 and the insulation resistance was less than 1.9,
which were not preferable.
On the other hand, in sample numbers 5, 8, 9 and 11, it was
confirmed that the content of BaTiO.sub.3 in the main component was
74.24 mol % and the preferable ranges of the properties were
confirmed to be all satisfied.
As shown in a sample number 34, when the content of BaTiO.sub.3
exceeded 79.97 mol %, it was confirmed that the dielectric loss was
deteriorated by becoming large as more than 1.7, the breakdown
voltage became low as not reaching 4.1 kV, and the electrostatic
capacity change rate with respect to temperature became large as
more than -55% at -25.degree. C.
On the other hand, in sample numbers 19, 22, 23 and 25, the content
of BaTiO.sub.3 was 79.79 mol % which in close to 79.97 mol % and
the preferable ranges of the properties were confirmed to be all
satisfied.
As shown in a sample number 14, when a content of BaZrO.sub.3 in
the main component was less than 5.69 mol %, it was confirmed that
the dielectric loss was widely deteriorated by becoming large as
exceeding 1.7, the relative permittivity became low as less than
9000, and the electrostatic capacity change rate with respect to
temperature became large as more than -55% at -25.degree. C.
Furthermore, in the sample number 14, the breakdown voltage was low
as less than 4.1 kV.
On the other hand, in the sample number 15, the content of
BaZrO.sub.3in the main component was 5.69 mol % and the preferable
ranges of the properties were confirmed to be all satisfied.
As shown in the sample number 35, when the content of BaZrO.sub.3
in the main component became more than 12.04 mol %, it was
confirmed that while the dielectric loss became small, the relative
permittivity became low as less than 9000, the insulation
resistance IR (.OMEGA.) became small as less than
1.9.times.10.sup.11 .OMEGA., and the breakdown voltage became low
as less than 4.1 kV.
On the other hand, in the sample number 27 wherein the content of
BaZrO.sub.3 was 11.09 mol % which is close to 12.04 mol %, the
preferable ranges of the properties were confirmed to be all
satisfied.
As shown in the sample number 35, when a content of CaTiO.sub.3 in
the main component became less than 7.84 mol %, it was confirmed
that the relative permittivity became less than 9000, the
insulation resistance IR (.OMEGA.) became small as less than
1.9.times.10.sup.11 .OMEGA., and the breakdown voltage declined as
not reaching 4.1 kV.
On the other hand, in the sample number 33, the content of
CaTiO.sub.3 in the main component was 7.84 mol % and the preferable
ranges of the properties were confirmed to be all satisfied.
As shown in sample numbers 14 and 32, when the content of
CaTiO.sub.3 exceeded 12.13 mol %, it was confirmed that the
relative permittivity became small as less than 9000 and the
insulation resistance IR (.OMEGA.) became low as not reaching
1.9.times.10.sup.11 .OMEGA..
On the other hand, in the sample number 18, the content of
CaTiO.sub.3 was 12.13 mol % and the preferable ranges of the
properties were confirmed to be all satisfied.
As shown in the sample number 29, when a content of MgTiO.sub.3 was
less than 3.11 mol %, it was confirmed that the insulation
resistance became small as less than 1.9.times.10.sup.22 .OMEGA.,
the breakdown voltage declined as not reaching 4.1 kV, and the
electrostatic capacity change rate with respect to temperature
become larger than -55% at +85.degree. C.
On the other hand, in the sample number 31, the content of
MgTiO.sub.3 was 3.11 mol % and the preferable ranges of the
properties were confirmed to be all satisfied.
As shown in the sample number 16, when the content of MgTiO.sub.3
exceeded 4.72 mol %, it was confirmed that the relative
permittivity became 9000 or less and the sintering property was
deteriorated.
On the contrary, in the sample number 17, the content of
MgTiO.sub.3 was 4.72 mol % and the preferable ranges of the
properties were confirmed to be all satisfied.
As shown in the sample number 2, when a content of
Bi.sub.2TiO.sub.5 became less than 0.10 mol %, the dielectric loss
was deteriorated by becoming large as exceeding 1.7, the
electrostatic capacity change rate with respect to temperature
became large as 55% or more at -25.degree. C., and the insulation
resistance declined.
On the contrary, in the sample number 3, the content of
Bi.sub.2TiO.sub.5 in the main component was 0.10 mol % and the
preferable ranges of the properties were confirmed to be all
satisfied.
As shown in the sample number 13, when the content of
Bi.sub.2TiO.sub.5 became more than 0.60 mol %, it was confirmed
that the relative permittivity declined to less than 9000, the
breakdown voltage became low as not reaching 4.1 kV, and the
sintering property was poor.
On the contrary, in the sample number 11, the content of
Bi.sub.2TiO.sub.5 was 0.60 mol % and the preferable ranges of the
properties were confirmed to be all satisfied.
As shown in sample numbers 6, 20 and 39, when a content of an
additive NiO became more than 0.1 wt %, it was confirmed that the
electrostatic capacity change rate with respect to temperature
became large as -55% or more at 85.degree. C., and the breakdown
voltage was deteriorated to less than 4.1 kV.
On the contrary, in sample numbers 8, 22 and 38, the content of the
additive NiO was 0.1 wt % and the preferable ranges of the
properties were confirmed to be all satisfied.
As shown in sample numbers 7, 21 and 42, when a content of an
additive CeO.sub.2 became more than 0.1 wt %, the electrostatic
capacity change rate with respect to temperature was confirmed to
be large as -55% or more at 85.degree. C.
On the contrary, in sample numbers 9 and 23, the content of the
additive CeO.sub.2 was 0.1 wt % and the preferable ranges of the
properties were confirmed to be all satisfied.
As shown in sample numbers 10, 24 and 47, when a content of an
additive MnO.sub.2became more than 0.2 wt %, it was confirmed that
the relative permittivity was widely declined to less than 9000,
the insulation resistance became less than 1.9.times.10.sub.11
.OMEGA., and the sintering property became poor.
On the contrary, in sample numbers 11, 25 and 46, the content of
the additive MnO.sub.2 was 0.2 wt % and the preferable ranges of
the properties were confirmed to be all satisfied.
According to the above results as shown in Table 1 and Table 2, to
satisfy the preferable properties, it was confirmed that preferably
0.1 wt % or less (excepting 0) of NiO, 0.1 wt % or less (excepting
0) of CeO.sub.2, and 0.2 wt % or less (excepting 0) of MnO were
contained with respect to 100 wt % of a main component
including
BaTiO.sub.3: 74.24 to 79.97 mol %
BaZrO.sub.3: 5.69 to 12.04 mol %
CaTiO.sub.3: 7.84 to 12.13 mol %
MgTiO.sub.3: 3.11 to 4.72 mol % and
Bi.sub.2TiO.sub.5: 0.10 to 0.60 mol % in total of 100 mol % of the
main component.
Evaluation 2
It was confirmed that as shown in sample numbers 36 to 38, 40, 41
and 43 to 46, the preferable properties were obtained even in the
case where the additive SiO.sub.2 was not added, while when a
content of SiO.sub.2 became more than 0.2 wt % as shown in sample
numbers 12, 26 and 50, the relative permittivity declined as not
reaching 9000, and the sintering property declined. Note that in
sample numbers 12, 26 and 50, adhesivity is exhibited during
firing. The adhesivity indicates a phenomenon that pre-sintered
elements arranged in a furnace react to adhere to each other during
sintering
On the other hand, in sample numbers 8, 22 and 49, the content of
SiO.sub.2 was 0.2 wt % and the preferable ranges of the properties
were confirmed to be all satisfied.
Furthermore, by comparing sample numbers 30 and 37 having exactly
the same composition except for SiO.sub.2, it was confirmed that
the insulation resistance and breakdown voltage improved when
SiO.sub.2 was contained, while the relative permittivity and
sintering property improved when SiO.sub.2 was not contained.
Evaluation 3
By comparing sample numbers 1 to 50 shown in Table 1 and Table 2,
to improve the relative permittivity to about 9200 or more and
satisfy the preferable ranges of other properties, it was confirmed
that preferably 0.1 wt % or less (excepting 0) of NiO, 0.1 wt % or
less (excepting 0) of CeO.sub.2, and 0.2 wt % or less (excepting 0)
of MnO were contained with respect to 100 wt % of a main component
including
BaTiO.sub.3: 74.38 to 79.79 mol %
BaZrO.sub.3: 7.33 to 10.15 mol %
CaTiO.sub.3: 8.34 to 12.13 mol %
MgTiO.sub.5: 3.40 to 3.76 mol % and
Bi.sub.2TiO.sub.5: 0.10 to 0.60 mol % in total of 100 mol % of the
main component.
Also, from the results shown in Table 1 and Table 2, by being
contained 0.04 to 0.10 wt % of NiO, 0.03 to 0.10 wt % of CeO.sub.2,
and 0.01 to 0.19 wt % or less (excepting 0) of MnO with respect to
100 wt % of the main component, it was confirmed that particularly
the relative permittivity became high and the insulation resistance
and sintering property ware also improved.
Furthermore, SiO.sub.2 may be contained also in the above
composition. In that case, the content thereof was confirmed to be
preferably 0.2 wt % or less.
As explained above, according to the embodiment of the present
invention, the dielectric ceramic composition having a high
relative permittivity, such as 9000 or more, and small
electrostatic capacity change rate with respect to temperature,
moreover, a high breakdown voltage can be obtained. Accordingly,
the dielectric ceramic composition according to the embodiment of
the present invention can be broadly used as a dielectric layer of
electronic devices.
As the electronic devices capable of using the dielectric ceramic
composition of the present invention, those electronic devices
requiring particularly a high permittivity used in an application
requiring a small electrostatic capacity change rate with respect
to temperature may be mentioned. Specifically, a ceramic capacitor,
multilayer capacitor, high frequency capacitor, high-voltage
capacitor, etc. may be mentioned.
Note that the present invention is not limited to the above
embodiments and a variety of modifications can be made within the
scope of the present invention.
* * * * *